The present invention relates to a portable, hand-held computing and indicating device for generating and visually displaying non-predictable codes and is adapted for use in a verification and identification system of the type described in the application Ser. No. 676,626.
There often arises a need to prevent all but selected authorized persons from being able to carry out some defined transaction (such as granting of credit) or to gain access to electronic equipment or other system, facility or data (hereinafter "clearance or access"). Prior methods for preventing unauthorized clearance o access typically involve devices which limit access to the subject data, facility, or transaction to those who possess a unique physical device, such as a key or who know a fixed or predictable (hereinafter "fixed") secret code. The problem inherent in relying on a fixed code or unique physical device as the means to gain such selective clearance or access is that would be unauthorized users need only obtain possession of the fixed code or unique device to gain such clearance or access. Typical instances of fixed codes include card numbers, user numbers or passwords issued to customers of computer data retrieval services.
Application Ser. No. 676,626 describes a system which provides a high level of security while permitting verification to be achieved without requiring any physical connection or electrical connection between the device in possession of the individual and a central verification device, thus permitting remote verification as by telephone. The system is also relatively simple and requires only one way communication from the individual seeking verification to the central verification computer. In particular, this system has a first computer which generates a first non-predictable code in response to a static variable applied to the computer, the non-predictable code being generated in accordance with a predetermined algorithm. The non-predictable code generated at a given time is displayed and may be communicated to a second computer at the verification station which computer generates a second non-predictable code utilizing the same algorithm and in response to the fixed variable and a second time dependent variable generated at the second computer. The two non-predictable codes are compared and verification is signified if the codes match. This invention relates to a portable hand held device which may be utilized as a first computer in the above system.